Hysteresis in the electromyography-force relationship: toward an optimal model for the estimation of force.

INTRODUCTION

In this study we analyzed the presence of hysteresis in the relationship between features of electromyography (EMG) and force.

METHODS

Intramuscular EMG and surface EMG (sEMG) were recorded concurrently from the flexor digitorum profundus muscle from 0% to 100% maximum voluntary contraction (MVC) in 11 subjects. Two features, mean absolute value (MAV) and Wilson amplitude (WAMP), were computed using either the first-order (poly1) or third-order (poly3) polynomial.

RESULTS

We detected hysteresis in the EMG-force relationship for both features in all subjects. In general, the hysteresis-based models performed better than the overall model (which does not take into account the hysteresis in the EMG-force relationship), with R(2) values about 0.98 (averaged across subjects) and root mean square error around 5% of the MVC force.

CONCLUSION

These results imply the existence of a path-dependent model, which may improve the accuracy of force estimation. Muscle Nerve, 2012.